Thrombin is a serine protease present in blood plasma in the form of a precursor, prothrombin. Thrombin plays a central role in the mechanism of blood coagulation by converting the solution plasma protein, fibrinogen, into insoluble fibrin.
Edwards et al., J. Amer. Chem. Soc. (1992) vol. 114, pp. 1854-63, describes peptidyl .alpha.-ketobenzoxazoles which are reversible inhibitors of the serine proteases human leukocyte elastase and porcine pancreatic elastase.
European Publication 363 284 describes analogs of peptidase substrates in which the nitrogen atom of the scissile amide group of the substrate peptide has been replaced by hydrogen or a substituted carbonyl moiety.
Australian Publication 86245677 also describes peptidase inhibitors having an activated electrophilic ketone moiety such as fluoromethylene ketone or .alpha.-keto carboxyl derivatives.
Thrombin inhibitors described in prior publications contain sidechains of arginine and lysine. These structures show low selectivity for thrombin over other trypsin-like enzymes. Some of them show toxicity of hypotension and liver toxicity.
European Publication 601 459 describes sulfonamido heterocyclic thrombin inhibitors, such as N-4-(aminoiminomethyl)amino!butyl!-1-N-(2-naphthalenylsulfonyl)-L-pheny lalanyl!-L-prolinamide.
WO 94/29336 describes compounds which are useful as thrombin inhibitors.